Walse et al disclosed a low insertion force electrical connector with stress controlled contacts in their U.S. Pat. No. 4,575,172 including each spring contact of the connector formed with a C-shaped portion with opposed arcuate contacting portions for engaging the conductive strips of the printed circuit board.
The C-shaped portion 70 of Walse's connector includes two opposed arcuate beam members 72, 74 for clamping a printed circuit board for electrical connection purpose. However, each arcuate beam member 72 or 74 is too short to have a longer force arm for a stronger resilience force effected by the C-shaped portion. The elasticity caused by such a conventional connector is still limited, thereby affecting its clamping force and its electrical connection efficiency.
In view of U.S. Pat. No. 3,848,952 invented by Charles I. Tighe, an electrical contact 22 and a follower contact 24 bifurcated from a yoke 20 which is secured to a cantilever 26, 28 connected to a contact support 30 are provided to clamp a print circuit board 18. Even its yoke 20 as secured to the cantilever 26, 28 can serve as a buffer for clamping a printed circuit board with a wider range of thickness. However, the two clamping members of the contacts 22, 24 bifurcated from the yoke 20 are still too short, so that the resilient clamping force caused by the two short contacts 22, 24 is quite limited, thereby influencing an efficient electrical connection between the contacts 22, 24 and the board 18.
It is therefore expected to further prolong a length of each spring contact of the two contacts clamping the printed circuit board to increase a force arm of an elastic force caused by the spring contacts in order to increase its clamping force of a contact element of an electrical connector.